We wish to continue to explore the effects of the major constituents of beverage alcohol (ethonol and congeners) on the aggressive behavior of fish. Fish have been chosen as a model system to study these effects for several reasons, not the least of which is the model, ethical and methodological obstacles to studying violent behavior in humans. Previous work has demonstrated that the fish is an excellent preparation for the study of aggression insofar as much is known regarding the stimuli reponsible for the elicitation and diminution of aggression in nature and laboratory replicas are easily constructed. Furthermore, the uptake, time course and metabolism of alcohol in man is more closely approximated in many respects by the fish than by more typical subjects for research, i.e. rodents. Two reports have shown increased aggression in fish treated with alcohol, and one demonstrated a lowering of aggression with congeners. We have replicated and extended this work to show an inverted U function between dose and aggressivity. In another study we have shown that the tri-weekly repetitions of the opportunity to aggress while intoxicated results in a gradual waning or habituation of the level of aggressivity. Fish treated similarly but without alcohol show no such dimunition. The methods used in our laboratory provide a multi-response description of the aggressive behavior of the species we use, Cichlasoma nigrofasciatum. The research proposed will focus on detailed analysis of the effects of alcohol and/or congeners on the elicitation and short and long-term habituation of interspecific aggression in C. nigrofasciatum. Armed with the results from the first parametric studies proposed, we will initiate investigations of the effect of alcohol intoxication of one member of a community of fish on the behavior of the members of the community. It is anticipated that these investigations will provide guidelines for future studies with primates and man directed at a comprehensive model of the role of alcohol in human aggression.